Reading specific part of a file

Question

Hi
Im trying to design a java program that reads a txt file such as the one below:
0 400 450 510 670 493 958
1 500 560 630 5633
2 625 676 740
3 1000 1250 1600
4 432
5 2435 235 2654
Then through a user prompt, outputs a specific number from a specific line to the user, i.e.
Line 1
Column 3
Would print 450
i have little knowledge of java, and im not sure if i need to read the whole file into arrays or i can get java just to read a specific line and column from it
i have tried using arrays but as the txt file can be of any size it got confusing!
Please help!
Thanks to you all

Answer 1

jverd is right.. you can use string tokenizer to seperate the columns of data via spaces.. or whatever you wanna specify. I'm seriously bored, so I wrote a working example for you that uses the data you posted
import java.util.*;
import java.io.*;
// usage:
// java Example <line> <column>
public class Example {
     public Example(int line,int col) throws IOException {
          col++; // because StringTokenizer will also count the first number of the actual line
          // example.txt has the data you posted...
          BufferedReader b = new BufferedReader(new InputStreamReader(new FileInputStream("example.txt")));
          String s = "",data = "";
          int j;
          while ((s = b.readLine()) != null) {
               if (Integer.parseInt(""+s.charAt(0)) == line) { // matches line
                    StringTokenizer st = new StringTokenizer(s); // separates words by space character
                    if (st.countTokens() < col) {
                         System.out.println("invalid column for line "+line+". there are only "+(st.countTokens()-1)+" columns on this line.");
                         System.exit(0);
                    // skip to the column..
                    for (j = 0;j < col;j++) data = st.nextToken();
                    System.out.println(data);
     public static void main(String[] args) {
          if (args.length < 2) System.out.println("use java Example <line> <column>");
          else try {
               new Example(Integer.parseInt(args[0]),Integer.parseInt(args[1]));
          catch (NumberFormatException e) {
               System.out.println("line and column need to be a number");
          catch (IOException e) {
               e.printStackTrace();
}